Liquid fuel burner system



Oct. 31, 1961 K. SHEW LIQUID FUEL BURNER SYSTEM Filed March 24, 1958.Znvezziop '12/ew United States Patent 3,006,407 LIQUID FUEL BURNERSYSTEM Kelvin Shew, Shirley, Solihull, England, assignor to Joseph Lucas(Industries), Limited, Birmingham, England Filed Mar. 24, 1958, Ser. No.723,299 2 Claims. (Cl. 158-363) This invention relates to a liquid fuelburner system of the kind which includes a burner of the swirl type anda spill return pipe, the object of the invention being to enable theflow in the spill pipe to be automatically regulated in a simple andreliable manner by providing and utilizing a controlling fuel flow whichis a fixed fraction of the fuel discharged by the burner for burning.

A system in accordance with the invention includes a pair ofproportional-flow valves as hereinafter defined and connectedrespectively to the burner supply and spill pipes, an intermediatepassage interconnecting the valves, a throttle in the spill pipe, meansadapted to bias the throttle to its closed position, a secondary spillpassage communicating with the spill pipe valve, and means dependent inpart on the pressure in the secondary spill passage for actuating thethrottle.

In the accompanying drawings:

FIGURE 1 is a part sectional elevation illustrating diagrammatically oneform of the invention.

FIGURE 2 is a fragmentary sectional view illustrating a modifiedfeature.

In the example illustrated by FIGURE 1 of the accompanying diagrams, theproportional-flow valve a through which the fuel is supplied from a feedpump b to a burner c along a supply pipe a, includes a main passage ewhich contains a restricted orifice f, and a chamber which is dividedinto two compartments g, i by a flexible diaphragm k. The compartment gcontains an outlet seating m with which co-operates a closure member ncarried by the diaphragm. Further the said compartment g is connected tothe main passage by a passage 0 to the upstream side of the orifice f,and in the passage 0 is contained a restricted orifice p the area ofwhich is a predetermined fraction of the area of the orifice f. Thecompartment i is connected to the main passage by a passage q at thedownstream side of the orifice f.

The proportional-flow valve through which fuel is spilled from theburner c to a sump or the inlet side of the pump b is similar inconstruction to the valve a, and corresponding components are identifiedby similar reference letters to each of which a suflix has been added,such as a g etc. The spillage from the burner is conveyed to the valve aby a pipe r. In this valve the compartment g communicates with thedownstream side of the orifice f and the compartment i communicates withthe upstream side of the said orifice.

The seating m in the valve a is connected to the compartment g of thevalve a by an intermediate passage s. Further the seating m of the valvea is connected to a secondary spill pipe I. From the valve a the spilledfuel passes to a throttle u, contained in a chambered body part v whichis divided into two compartments w, x by a diaphragm y. The throttle isattached to the diaphragm, and to the opposite side of the diaphragm isattached a tension spring z which biases the throttle to its closedposition. Further, the secondary spill passage t communicates with thecompartments w, x at opposite sides of an aperture 4 which is controlledby an adjustable plug 5.

Starting with the system in the condition represented by FIGURE 1, themode of action is as follows:

On starting the pump, the first efifect of the pressure of the fuel isto lift both of the closure members n, n of the valves a, n off theirseatings, and so enable the throttle u to be moved to its fully openposition against the action of the spring z by the pressure of the fuelin the secondary passage acting on the diaphragm y. So long as it is required to effect a low rate of discharge of fuel from the burner thiscondition is maintained, and a sufiiciently large proportion of the fuelis returned by the spill pipe to ensure the desired effectivenebulization of the discharged fuel. To obtain an increased dischargefrom the burner the plug 5 is retracted from the associated aperture 4,thus diminishing the fuel pressure difference acting on the diaphragm y,and enabling the spring z to return the throttle towards its closedposition. When this pressure difference is sufliciently reduced, thethrottle is moved to its fully closed position, and in this conditionthe Whole of the fuel supplied by the pump is discharged through theburner.

The actuation of the plug 5 may be effected by any convenient meansresponsive to a variable factor associated with the working of thesystem supplied with fuel by the burner. Such a factor may be the speedof an engine driven by the combustion products. Another factor may be achange of atmospheric pressure due to a change of altitude, or pressureof the combustion air supplied by a blower. Still another factor may bethe temperature in the combustion chamber acting on a thermometricdevice. Moreover, the plug may be actuated by manually-operable means.

An alternative means for actuating the throttle is illustrated by FIGURE2. In this example a constantly open aperture 4 is provided in thesecondary spill passage, this aperture being of appropriate size tomaintain a given fuel pressure difference at the opposite sides of thediaphragm y, and movement of the throttle is effected by varying thetension of the spring 2. In the example illustrated one end of thespring is attached to slidable actuator 6 which is movable by, forexample, a pinion 7 acting on a rack 8, the pinion being movable by anyof such factors as those above mentioned, and also, if desired, bymanually-operable means.

The design of the system above described is such that over a normalrange of Working, the ratio of the fuel flow through the orifice and theflow through the orifice p is constant. Also the ratio of the flowthrough the orifice f and the flow through the orifice 12 is equal tothe said constant. Further the ratio of the difference of the flows inthe pipes d and r, and the difference of the flows in the pipe s andorifice p is also equal to the said constant. Consequently, the flowthrough the secondary spill passage t is a fixed fraction of the fueldischarged by the burner c for burning. Thus, the fuel flow through theintermediate passage s to the compartment g of the valve a is a fixedproportion of the fuel flow through the supply pipe d, and as the fuelflow from the compartment g through the orifice p is a correspondingfixed proportion of the fuel flow through the spill pipe r, it followsthat the fuel flow from the compartment g through the secondary spillpassage t is, as indicated above, a fixed fraction of the fueldischarged by the burner for burning.

From the foregoing it will be seen that the fuel flow through thesecondary spill passage t is used for regulating the flow in the spillpipe r, and is attained by the joint effect of the two proportional-flowvalves a and a Having thus described my invention what I claim as newand desire to secure by Letters Patent is:

l. A liquid fuel burner system comprising in combination a burner of theswirl type, a fuel pump, a fuel supply pipe leading from the fuel pumpto the burner, a spill pipe leading from the burner, a pair of similarproportional-fiow valves connected respectively to the fuel supply andspill pipes, each valve having a closure member, a pressure-responsivemember carrying the closure member, a chamber divided by thepressure-responsive member into two compartments, a main passageprovided at a position intermediate its ends with a restriction andinterconnecting portions of the pipe to which the corresponding valve isconnected, an unrestricted passage connecting one of the twocompartments to the main passage at the side of the restriction thereinnearest to the burner, a restricted passage connecting the othercompartment to the main passage at the other side of the restrictiontherein, and a seating for the closure member in the said othercompartment, a passageway communicating at opposite ends respectivelyWith the seating of the valve connected to the fuel supply pipe and withthe said other compartment of the valve connected to the spill pipe, athrottle in the spill pipe at a position further from the burner thanthe valve connected to the spill pipe, means adapted to bias saidthrottle to its closed position, a secondary spill passage communicatingwith the seating of the last mentioned valve, means for creating apressure difference in the secondary spill passage, and means responsiveto the pressure difference in the secondary spill passage for actuatingthe throttle.

2. A liquid fuel burner system according to claim 1, and comprising achambered body part divided into two compartments by apressure-responsive member constituting the means responsive to thepressure difference in the secondary spill passage for actuating thethrottle, a spring constituting the means adapted to bias the throttleto its closed position, and adjustable means for varying the pressuredifference in the secondary spill passage, the two compartments of thebody part being in communication with the secondary spill passage atpositions for enabling the different pressures in the secondary spillpassage to act on opposite sides of the throttle-actuating member.

References Cited in the file of this patent UNITED STATES PATENTS2,265,961 Ziebolz Dec. 9, 1941 2,698,141 Dickey et a1. Dec. 28, 19542,738,003 Carey Mar. 13, 1956 2,806,519 Basford et a1. Sept. 17, 1957

